The clarinet forms part of the woodwind family of instruments. It generally consists of five joinable parts: the mouthpiece, the barrel joint, the upper joint, the lower joint and the bell. These parts are generally connected by means of cork-wrapped tenons and corresponding seatings for these tenons, which are provided on each individual part at the relevant points of connection. If all five parts of the clarinet are fitted together, such that there are no gaps between the individual parts, a continuous bore of essentially uniform internal diameter will be formed in the interior of the clarinet, extending from the mouthpiece, through the barrel joint, the upper joint and the lower joint down to the bell.
As the musical repertoire of the clarinet includes pieces for soloists, as well as pieces for chamber groups and orchestras of various compositions, it is necessary for instruments to be tuned to each other, particularly where a number of musicians are playing in consort. In this regard, the pitch of a given note will depend upon instrument-specific factors and upon variable environmental influences, specifically the ambient temperature, which will have a direct impact upon the temperature of the instrument. In all woodwind instruments, the pitch of a given note will rise as the temperature of the instrument increases.
Where a number of musicians are to play in consort, instruments will generally be tuned to each other before the start of playing. As wind instruments are warmed by the stream of warm air from the player's lungs, it will generally be necessary to retune instruments in the course of concert playing. Many works or pieces of music also require a change of instrument, e.g. from an A clarinet to a Bb clarinet, in the course of piece, such that the clarinet not in use will cool down again, and will require retuning as a result.
In all wind instruments, the longer the vibrating column of air in the instrument, the lower the resulting note will be. The lengthening of the vibrating column of air is generally achieved by slightly pulling out one or more parts of the instrument. In the case of the clarinet, a deeper pitch is generally achieved by drawing the barrel joint a little further out of the upper joint or out of the mouthpiece.
By this action of withdrawal, the above-mentioned continuous bore at the point of connection, e.g. between the barrel joint and the upper joint, will be extended by a length which corresponds to the withdrawal concerned. The resulting internal hollow space and external gap will adversely affect the tonal qualities and intonation of the instrument, and will also form a site for the accumulation of unwanted condensation, which will impair the playing qualities of the instrument. Immediately the barrel joint is pulled out of e.g. the upper joint, the only remaining connection between these parts of the clarinet will be formed by the sound-damping cork, with a resulting impairment to the tone of the instrument.
The provision of a metal sleeve for the bridging of the hollow space is known e.g. from U.S. Pat. No. 1,416,898, whereby the said sleeve is inserted telescopically into the clarinet bore and can be removed from the latter. However, on the grounds of the complexity of mounting a sleeve of this type, together with the influence of the insertion of a metal component upon the tone of the instrument, a mechanism of this type has not been introduced into clarinet construction to date.
The formation of the barrel joint as a two-part wooden component, comprising an upper part and a lower part, in which the above-mentioned sleeve is incorporated integrally to one part of the barrel joint, is also known. A sleeve of this type, configured integrally to part of the barrel joint, is disclosed e.g. in U.S. Pat. No. 5,249,499. The clarinet barrel joint described herein comprises an upper part and a lower part, whereby a set collar is provided between the upper part and the lower part for the connection thereof. The upper part is screwed into the set collar, and the lower part is arranged to rotate on the set collar. By the rotation of the set collar, the axial distance between the upper part and the lower part can be adjusted.
A drawback of this arrangement is the fact that, upon the rotation of the set collar, the upper and lower parts of the barrel joint can essentially rotate in opposite directions. The rotation of the lower part of the barrel joint simultaneously to the movement of the set collar is prevented by the rotatable mounting of the lower part on the set collar. If this is to be achieved, the lower part must show the least possible resistance to the rotational movement of the set collar. However, this means that, even under normal playing conditions, the lower part of the barrel joint will be very easily rotatable in relation to the set collar and the upper part of the barrel joint, which is a substantially undesirable characteristic.